The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Increasing fuel economy is a desirable goal for auto manufacturers. Consumers desire high fuel economy without sacrificing performance. Turbocharging provides a method for increasing performance during demanding conditions while reducing the overall fuel economy of the vehicle since a smaller displacement engine can be used.
One type of turbocharging system is a parallel turbocharger. In such a system, two turbines are provided in parallel and are capable of running simultaneously. In one mode of operation one turbine is spinning (on) while the other is not spinning (off). This mode will be referred to as single turbocharger mode. In another mode of operation both the turbines are spinning. This will be referred to as dual turbocharger mode. Providing a smooth transition between the modes is important for drivability of the vehicle.